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brute_force.go
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/
brute_force.go
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/*
* Copyright (c) 2018 XLAB d.o.o
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package dlog
import (
"fmt"
"math/big"
"github.com/fentec-project/bn256"
)
// Simply brute-forces all possible options.
func bruteForce(h, g, p, bound *big.Int) (*big.Int, error) {
if bound == nil {
bound = new(big.Int).Sub(p, big.NewInt(1))
}
for i := big.NewInt(0); i.Cmp(bound) < 0; i.Add(i, big.NewInt(1)) {
if new(big.Int).Exp(g, i, p).Cmp(h) == 0 {
return i, nil
}
}
return nil, fmt.Errorf("failed to find discrete logarithm within bound")
}
// Simply brute-forces all possible options to compute dlog in BN256 GT group.
func bruteForceBN256(h, g *bn256.GT, bound *big.Int) (*big.Int, error) {
if bound == nil {
bound = bn256.Order
}
for i := big.NewInt(0); i.Cmp(bound) <= 0; i.Add(i, big.NewInt(1)) {
t := new(bn256.GT).ScalarMult(g, i)
if t.String() == h.String() {
return i, nil
}
}
return nil, fmt.Errorf("failed to find discrete logarithm within bound")
}